Electric clock



April 13, 1937. A, F P LE 2,077,007

ELECTRIC CLOCK Filed Nov. 4, 1930 Joanie/l6! or.

INVEN OR.

Patented Apr. 13, 1937 UNITED STATES PATENT OFFICE ELECTRIC CLOCK Application November 4, 1930, Serial No. 493,312

20 Claims.

My invention is an improvement in electric clocks. The'object of my invention is to provide a new and improved method of bringing a clock into synchronism with a source of governed periodic or alternating current. By governed alternating current I mean a current whose frequency is held exactly to a predetermined value by comparison, either automatic or manual, with a master clock. This current is distributed over the line wires customarily employed to distribute light and power and is used to actuate clocks containing synchronous motors at any power or light outlet and currents of this kind are Well known in the art, having been used for a numher of years.

Clocks of this kind have a drawback that if the source of current is interrupted all of the clocks connected to the line will stop, and in the event the current comes on again the clocks will either start themselves or have to be started byhand. In any event the clocks are slow the length of time the current has been interrupted.

It is one object of my invention to bridge over this period of interruption of current so that the clocks will continue to function for a limited time notwithstanding the fact that the current has been cut off. Another object of my invention is to. provide a synchronous motor in connection with an ordinary clock mechanism and to provide 30 means for holding the clock mechanism in syn chronism with the rotations of the motor, thus causing the clock to run in step with the motor.

A further object of my invention is to provide an improved and simple mechanism for the above 35 purpose said mechanism operating directly on the vibrating member of the clock in order to maintain it in synchronism. Another object of my invention is to render the said synchronizing means inoperative when the current supply is interrupted. These and other objects of my invention will appear in the following specification and drawing and will be set forth in the claims.

Referring now to the drawing, Fig. 3 is a perspective view of the parts of a clock which cooperate with my improved mechanism. In this particular illustration, the clock illustrated is a clock governed by a balance wheel hair spring. Fig. 4 is a view of my invention as applied to a pendulum clock. Figs. 1 and 2 are views of different positions of the balance springof Fig. 3. All of the above figures are more or less diagrammatic and show only the parts of the clock mechanism cooperating with my herein described in- 55 vention. The remaining clock parts are omitted,

since they are well known in the art and may easily be supplied by those skilled in it. Referring particularly to Fig. 3, l0 and II are light or power mains carrying a governed alternating or periodic current whose frequency is kept in synchronism with a master clock at the power house- This current is preferably stepped down by a suitable transformer (not shown) from the high line voltage. A synchronous motor l2, preferably of the self-starting type, is connected to H1 and II and consequently runs in step with the current.

A clock is provided of which the escape wheel I3 is shown mounted on its staff l4 rotatably mounted in the clock framework. The escape wheel l3 may be driven by a hand wound spring or by an electric winding mechanism operated from the power circuit, as shown in my Patent No. 1,328,247 issued to me January 13, 1920, particularly in Fig. 2 thereof. The rotation of the escape wheel I3 is governed by the pallets l5 mounted on a shaft l6 rotatably mounted in the framework. A fork I! is mounted on the shaft l6 and through the roller pin l8 gives impulses to a balance wheel. l9 mounted on a shaft 20 and whose vibrations are governed by a hair spring 2|. The customary regulator 22 with curb pins 23 and 24 mounted in it is provided. The regulator 22 is rotatably mounted in the framework so as to be concentric with the balance staff 20 but not in contact with it.

All of the above described parts from l3 to 24 inclusive are old and well known in the art and do not need further description. I will now describe the parts peculiar to my present invention and which serveto keep the vibrations of the balance in step, with the frequency of alternating current supply.

A synchronizing lever 25 is rotatably mounted at 26 on the end of a bell crank 21 rotatably mounted at 28 in the framework. The bell crank 21 is made of iron and the arm 29 is held in contact with a stop 30 against a spring 3| by a magnet 32 supplied with current from the mains l0 and l I. One end of the lever 25 carries a pin 33 adapted to contact with the hair spring 2| and the other end of the lever 25 is held in contact with a specially shaped cam 34 by a spring 35. The function and shape of the cam 34 will be hereinafter described. The cam 34 is mounted on a shaft 35 which carries a gear 31 meshing with a pinion 38 on the shaft 39 of the synchronous motor l2. The speed of the motor and the ratio of the gear 31 and the pinion 38 is such that normally the pin 33 vibrates approximately in synchronism with the balance spring 2| but without touching said spring. When this condition obtains, I hereinafter speak of the spring 2| and the pin 33 as 5 vibrating in phase. Now suppose the balance |9 lags or gets behind the phase of the pin 33. Then said pin when it moves toward the staff 20 will contact with the spring 2| for the reason that the spring has not as yet gotten out of the way. 0 This contact will accelerate the balance l9 which will tend to bring the balance I9 and spring 2| into phase again. The balance I9 is timed to run a little slow and therefore the action of the pin 33 is to impose an intermittent acceleration on the balance l9 each time the balance gets out of phase. This acceleration will be repeated until the balance is brought into phase again when the accelerating action of the pin 33 will temporarily cease. However the balance will run slow and the pin 33 will come into action again.

This condition of the balance vibrating alternately fast. and slowwill continue'as long as current is supplied to the motor l2. Therefore'in the long run the vibrations of the balance will be exactly in step with the frequency of the alternating current. s

The synchronizing action of the pin 33 is shown more clearly in Figs. 1 and 2, where Fig. 1 shows the balance spring 2| when the balance I9 is in phase. The full lines show the at rest position of the-spring 2| and'the pin 33. 2| and 33' show the expanded-position of the spring 2|- and corresponding position of the pin 33. 2| and 33" show the contracted position of the spring 35 2| and the corresponding positions of the pin 33.

Fig. 2 shows the relative position of the spring l9, and the pin 33 when they are out of phase, 2| and 33' and 2| and 33" representing the expanded and contracted positions of spring 3| and pin 33 respectively.

It is to be observed that when the spring 2| and pin 33 are out of phase, as in Fig. 2, the pin 33 does not touch the spring 2| when said spring is in its expanded position, but touches it only as the spring 2| is contracting; The pin'33 follows the spring 2| towards the balance staff 29 as the spring 2| is contracting- When said spring has reached its contracted position the pin 33 is suddenly withdrawn from the path of the spring 2| by the cam 34 which is'so shaped as to perform this sudden withdrawal.

If pin 33 were to contact with spring 2| when said spring is expanding the result would be to accelerate the balance I9 through a whole cycle.

While this result would be undesirable it would not be serious since it would result in the cl'ocks gaining one-half second (assuming the balance I9 has 129 cycles per minute) and would be compensated for in whole or in part during the period of current interruption since the clock is adjusted to run a trifle slow. As before noted, when the current supply is interrupted the motor I2 stops and consequently at that time the pin 33, unless some means were provided to prevent it, might stop in a position where it would be touched at each vibration of the hair spring 2| and thus cause the clock to run considerably fast during the period of no current. overcome this difliculty, I have provided the magnet 32 which is'supplied with current such that normally it will hold the arm 29 against the stop 39. If, however, the current fails the magnet 32 is de-energized and the spring 3| pulls the 75 arm 29 against the stop 40 thereby rotating the In order to balance crank and moving the point 26 on the arm 25 in a counter clockwise direction, since the end of the lever 25 is held by the spring 35 against the cam 34. This rotation will move the pin 33 out of the way of the hair spring 2|, and said spring will vibrate unaffected by the pin 33.

During the period of no current the clock continues to run without being accelerated by the action of the pin 33 and. will lose more or less time according to the duration of the period of no current. When the current again comes on, the magnet 32 will be energized, the arm 29 will be pulled against the stop 30, the motor l2 will start, and the pin 33 will shortly bring the balance IS in phase with the motor l2 and maintain it there.

Since the clock is regulated to lose about 15 seconds per day the time lost during a period of current interruption will be small and will in part be compensated for by the acceleration of the pin 33, as noted above.

In Fig. 4 I have shown my invention applied to a pendulum clock of which I have shown the pendulum and synchronizing device only. The pendulum may be maintainedby a hand wound mechanism or by an electrically wound one. Fig. 4, the pendulum 4| has a light spring 42 attached thereto. The synchronizing action is analogous to that shown in the mechanism in Fig. 3, the parts having similar movements to corresponding parts in Fig. 3; except the numbers in Fig. 4 have been primed. Thus the lever 25 is pivoted at 26' at the end of a bell crank 29' pivoted at 28-, in the framework. The arm of thelever 29 is held in its position by the magnet 32', thereby placing the pin 33' in a position to act on the spring 42 attached to the pendulum 4|. The arm 25' is actuated by the motor l2 through the train of gears 21 and the cam 34. Thesynchronizing action is the same as in the mechanism shown in Fig. 3, the pendulum 4| being timed to run a trifle slow and being accelerated by the action of the pin 33' as described in the corresponding mechanism of Fig. 3.

My herein described invention is not limited to any precise form of clocks. It will workequally well on a clock governed by a balance wheel or on a clock governed by a pendulum. It will be especially useful as applied to a tower clock where there is a massive mechanism required to turn the large hands which are used in such clocks, and further, it is not necessary that the existing clock be at all changed, since my improved mechanism may be applied to any tower clock by simply placing the accelerating spring 42 on the tower clock pendulum and providing the synchronous motor l2 and its associated train of mechanism. By this means the tower clock may be kept in step with an alternating current. It is tobe understood that it is necessary that the vibrating member of the clock be regulate so as to run always slow. The action of the pin 33 is always to accelerate the pin I9, or the pendulum 4|, as the case may be. As long as the alternating current is on, theclockwill be synchronized. When-the current is interrupted, the clock will keep going at nearly the right rate until the current comes on again, when it will be brought into step by the action of the pin 33.

I have described the ball crank 29 as made of iron. This is not necessarily so, for it could be made of some nonmagnetic metal and an armature could be fastened to the end 29 to be acted on bythe magnet 32.

Many variations and changes may be made in the precise structure herein shown without departing from the spirit of my invention, since I claim:

1. In combination, a synchronous motor, a vibrating member operating at a rate slightly slower than the rate desired, elastic means affecting the time of vibration of said member, and means operated by said motor at each vibration of'said member and acting onsaid elastic means throughout substantially the full movement of said member in one direction to increase momentarily the rate of said member and bring it into phase with said motor.

2. In combination, a source of regulated current, a synchronous motor connected to said source, a vibrating member having anatural rate slightly less than desired, elastic means aifecting the time of vibration of said member, means governed by saidmotor and operating on said elastic means throughout substantially the full movement of said member in one direction to increase momentarily the natural rate of said member and bring said member into phase with said current.

3. In combination, a synchronous motor, a vibrating member, elastic means affecting the time of vibration of said member, a floating lever governed by said motor and operating on said elastic means at each vibration thereof to bring said member in phase with said motor, and means for shifting said lever into and out of operative positions with respect to said elastic means.

4. In combination, a synchronous motor, a cam rotated by said motor, a, vibrating member, elastic means affecting the time of vibration of said member, a lever operated by said cam and operating under the direct force of said cam on said elastic means at each vibration thereof to bring said member in phase with said motor, and means yieldingly urging said lever against said cam and in a direction to stop said lever from stressing said elastic means, said cam and urging means co-operating to retract said lever out of influencing relation with said elastic means quickly after each complete action" thereon in one direction to enable unrestrained movement of said member in the opposite direction.

5. In combination, a synchronous motor, a vibrating member, elastic means affecting the time of vibration of said member, means governed by said motor and operating on said elastic means at each vibration thereof to bring said member in phase with said motor, an electromagnet, and mechanism controlled by said electromagnet rendering said motor governed means operative or inoperative.

6. In combination, a synchronous motor, a vibrating member, elastic means affecting the time of vibration of said member, means governed by said motor and operating on said elastic means at each vibration thereof to bring said member in phase with said motor, an electromagnet, means for energizing said electromagnet, and

mechanism operative on the de-energization of said electromagnet to render said motor governed means inoperative on said elastic means.

7. In combination, a synchronous motor, a pendulum having a natural period slightly less than desired, an accelerating spring operative on said pendulum, and means operated by said synchronous motor and effective upon said spring throughout substantially an entire arc of oscillation of said pendulum in one direction to bring said pendulum in phase with said motor by momentarily stressing said spring to accelerate temporarily the vibration of said pendulum.

8. In combination, a synchronous motor, a pendulum having a natural period slightly less than desired, an accelerating means operative on said pendulum, a lever oscillated by said synchronous motor at the exact rate desired for said pendulum, and means mounted on said lever and contacting with said accelerating means. throughout its complete arc of movement in one direction to accelerate as necessary the rate of said pendulum at any point in said complete arc of movement in order to bring the pendulum into phase with said motor.

9. In a clock system, a source of periodic current having a governed-uniform periodicity, an elastic vibratory part having a natural period which is slightly less than one which bears approximately a simple relation to the periodicity of said current, and means governed by said current, and engageable automatically with said elastic part to increase temporarily its natural period and alter its phase whenever said part lags out of step with the fluctuations of said current.

10. In a clock system, a source of periodic current having a governed, uniform periodicity, an elastic vibratory part having a natural period which bears approximately a simple relation to the periodicity of said current, means governed by said current, and engageable automatically with said elastic part to change its natural period and altering its phase whenever said part gets out of step with the fluctuations of said current, and means for freeing said part from the influence of said governed means upon failure of said current.

11. In combination, a vibratory member, a hair spring controlling the natural period of vibration of said member which is slightly less than the desired rate, a motor responsive to a periodic current, and means controlled by said motor and operable back and forth at the desired period for said member in a direction radially of the center. of said spring through a con siderable part of the movement of said spring to engage said spring and increase temporarily the natural period of said member whenever the periodof said member decreases below that of said means, so as to bring the period of said member into a definiterelation to the periodicity of the current to which said motor is responsive, said means moving idly with respect to said spring when, in phase therewith.

12. In combination, an oscillating balance wheel, a hair spring controlling the operation of said balance wheel, a source of periodic current, and means controlled by said current, normally free of engagement with said hair spring when said balance wheel is oscillating with a frequency bearing a desired relation to the periodicity of said current, but engageable with said hair spring tochange its natural period whenever said balance wheel departs from said frequency.

13. In combination, a synchronous motor, a vibrating balance wheel, a hair spring controlling the period of vibration of said balance wheel, a lever shiftable into and out of engagement with said hair spring, and means controlled by said motor for rocking said lever toward and from said hair spring in a definite phase relation to the operations of said motor, said lever causing no pressure on said spring when said wheel is operating in phase with said lever, but engaging and distorting said hair spring and altering the period of said balance wheel when said. wheel departs from its phase relation to said lever.

14. In combination, a synchronous motor, a vibrating balance wheel, a hair spring controlling the period of vibration of said balance wheel, a lever shiftable into and out of engagement with said hair spring, means controlled by said motor for rocking said lever toward and from said hair spring in a definite phase relation to the operations of said motor, said lever causing no pressure on said spring when said wheel is operating in phase with said lever, but engaging and distorting said hair spring and altering the period of said balance wheel when said wheel departs from its phase relation to said lever, and electro-magnetic means controlling said lever and shifting it into and out of a position in which it is operative upon said hair spring.

15. In a clock system, a clock train'having a vibrating time measuring element maintained in operation thereby, a synchronous motor, a member maintaining contact with said element through the major part of 'each vibration'in one direction, means controlled by said motor for operating said member at the rate desired for said element during said contact and operable to quickly remove said member from engagement with said element after a predetermined movement of said member in a following direction, and then to forcibly hold it so removed and while so held move it in the opposite direction in advance of said element, whereby said member will be forcibly held out of contact with said element during return, vibratory movement of said element.

16. In a clock system, a clock train having a time measuring element vibrated thereby, a member mounted to engage and follow said element through substantially'the full arc of movement of said element while said element is moving in one direction and to advance away from said element during movement in the other direction, a motor, means governed by said motor and operating said member to engage and impart a continuous driving movement to said element while said member is following said element and throughout substantially the entire following movement whenever movement of said element lags behind the rate of operation of said member, and keeping said member well in advance of said element during movement in the other direction in which said member precedes said element.

1'7. In a clock system, a clock train having a time measuring element vibrating approximately at a desired rate, a motor, a cam rotated by said motor, and means controlled by said cam and including a member moved in a back and forth direction in timed relation to the operation of said motor, a part of said member continuously engaging and following said element through substantially the full arc of movement'of said element during movement in one direction and preceding it during movement in the opposite direction, said'oam having a shape such that it causes movement of said member well in advance of said element in said opposite direction, and at the rate desired for said element when following said element in said one direction whereby said member will engage and compel movement of said element at the rate of saidmember during movement of said element in one direction only.

18. In a clock system, a clock train having a vibrating balance unit, a hair. spring connected to said balance unit and determining the natural rate of vibration of said balance unit; a member mounted for,v movement toward and from a turn of said hair spring, so as to follow said turn when said hair spring is moving in one direction and to precedesaid turn during movement of the hair spring in the other direction, .whereby if said member is moving back and forth at the same rate as said hair springand in phase therewith, said member will not engage and exert pressure on said hair spring when following it, means for moving said member back and forth accurately at the rate of vibration desired for said hair spring whereby if said hair spring and balance unit lag in phase behind said member, said member while following said turn will engage and stress the hair spring and accelerate the natural rate of vibration of said balance unit and hair spring until the balance unit and hair spring are again vibrating in synchronism with said member.

19. In a clock system, a vibrating time measuring element, including a hair spring which controls its normal rate of vibration, a vibratory member having a portion in proximity to said hair spring and following the hair spring in close proximity thereto while said hair spring moves a relativelyconsiderable distance in one direction,means for vibrating said member at a rate approximately that of the hair spring and at the exact rate desired for said hair spring, whereby when said element and member are vibrating in step with one another, said member will move idly'with respect to said hair spring and when said element lags, said member will engage said hair spring and accelerate its movement in one direction to accelerate the rate of said element untilsaid element and member again vibrate in step withone another.

20. In a clock system, a vibratory time measuring element including a hair spring controlling its natural rate of vibration and giving said element a natural rate of vibration slightly less than that desired for said element, and means for engaging and imparting stresses to said hair spring to increase the natural rate of vibration of said element automatically whenever said rate falls below the rate desired for said element, and imparting no stresses to said hair spring when said element is vibrating at said desired rate.

ARTHUR F. POOLE. 

